FITCHES1 has convincingly demonstrated the relative insignificance of the Pan-African orogeny in a part of coastal Ghana. He disputes the importance of this orogeny elsewhere in West Africa, however (Fitches, personal communication), as implied in his Fig. 1b of ref. 1, which shows no change in tectonic style eastwards. Contrary to this view, my results from recent mapping in northern Nigeria (unpublished) support Grant2,3 and other workers4,5 in recognizing a complete orogenic event in late Pre-Cambrian times. Moreover, it has been possible for. the first time to define two major successive episodes of deformation which affected both basement rocks and the metasedimentary cover. It is aimed to show how these two deformational phases in Nigeria and the contrasting tectonic style in coastal Ghana, can be related to modern theories of ocean contraction and plate tectonics (ref. 6 and unpublished work of K. C. Burke and J. F. Dewey).